A conventional image forming apparatus includes a photosensitive member, a transferring device, and a scraper. In this image forming apparatus, a coefficient of dynamic friction of a surface of the photosensitive member increases as image formation operations are repeatedly performed. When the coefficient of dynamic friction increases, toner is hard to be removed from the surface of the photosensitive member, and resides on the surface of the photosensitive member. Once the toner resides on the surface of the photosensitive member, the toner on the surface of the photosensitive member moves to a sheet during a subsequent image formation operation, thereby reducing quality of the image.
In a conventional image forming apparatus, which is disclosed in Japanese Patent Application Publication No. 2006-234894, a scraper scrapes a surface of a photosensitive member in order to reduce a coefficient of dynamic friction when a torque current arrived at a prescribed value on the basis of an assumption that there is a correlation between the coefficient of dynamic friction of the surface of the photosensitive member and the torque of the photosensitive member.